As tesla folks said on recent earnings call, this requires a lot of work of the FSD licencee, about 3 years from start to finish. This is technically doable.
A more fundamental question is revenue from FSD, is it something (subscription) people will pay for it as an extra item or is it considered a safety feature like seat belt and backup camera, which is baked into the car price by default.
From Tesla recent 10q, there are 5 mentions of FSD, and its deferred $ is not promising per financial reporting ($3.5 bn unchanged from prior reporting period).
So after 12.3.x free trial, the take rate is a critical indicator, is it a toy or real must for mass market at $1200/year. I asked 4 friends recently, they all love FSD but none wants to pay $99. I am also on the fence. On the flip side of this, if my auto insurance company says that we deem FSD so safe and can give me a rebate of $100 for my model y monthly premium, I would pay $99 FSD. But this is unlikely, as my auto insurance premium is just $101 a month.
So in my view, FSD has little revenue effcet.